Species Description: The goldspotted killifish, Floridichthys carpio, is one of three recorded North American species of the family Cyprinodontidae (Nordlie 2006). Members of this family are characterized by a single, spineless dorsal fin, abdominal pelvic fins, squared or rounded caudal fin and a scaly head (Robins & Ray 1986). The body of F. carpio is short, deep and chubby, with convex dorsal profile (Robins & Ray 1986). Darker irregular bands are present on the lower sides, and the lack of a dark spot at the base of the first dorsal fin ray differentiates this killifish from similar species. Breeding males are more brightly colored, with orange-gold spots on the cheeks and body.
Potentially Misidentified Species: The goldspotted killifish may be mistaken for the sheepshead minnow, Cyprinodon variegatus. This species is similar in shape and coloration, and may be found inhabiting the same areas as F. carpio in the IRL. The dorsal surface of C. variegatus is less concave, and the irregular dark bands extend over most of the side (Robins & Ray 1986). A dark spot is present at the base of the first dorsal fin ray, which is especially prominent in young individuals. Males have a dark edged caudal fin, and breeding males are brightly colored with a blue nape, orange cheeks and lower parts, and lack dark bands. Females have an ocellus, or eyespot, on the rear of the dorsal fin. At a maximum length of 7.5 cm, sheepshead minnows also grow slightly larger than goldspotted killifish.
Regional Occurrence & Habitat Preference: The range of F. carpio extends from southeast Florida through the Gulf of Mexico (Robins & Ray 1986). Populations are found in shallow coastal habitats such as: seagrass beds (Sogard et al. 1987), especially those with sparse cover (Sogard et al. 1989); mangroves (Thayer et al. 1987); salt marshes; and mosquito impoundments (Lewis & Gilmore 2007, Stevens 2002).
IRL Distribution: Though the specific boundaries of the IRL distribution for F. carpio are unknown, populations can be found in many regions of the lagoon. Most fish are concentrated in mangrove and salt marsh areas, including portions impounded for mosquito control.
Age, Size, Lifespan: Information concerning the maximum age and average lifespan of F. carpio is lacking. Growth rates vary with environmental conditions, food availability and other factors. The maximum reported size for the goldspotted killifish is 6.5 cm (Robins & Ray 1986).
Abundance: Abundance estimates for F. carpio in the IRL have not been reported. However, this species was found to the second most abundant fish in Florida Bay, outnumbered only by the rainwater killifish, Lucania parva (Sogard et al. 1987). Mean densities of fish throughout Florida Bay exceeded 3 individuals m2 (Sogard et al. 1987), with the largest populations found in September and November (Schmidt 1979).
Reproduction: Little information is available detailing the reproduction and embryology of F. carpio. Sexual maturity is attained during the first year (Powell et al. 2007). Females spawn multiple times throughout the year (Nordlie 2000, Powell et al. 2007), laying eggs one at a time on benthic substrata (Nordlie 2000).
Salinity & Temperature: The goldspotted killifish occupies marine and estuarine areas, occasionally entering freshwater (Robins & Ray 1986). Populations have been found in salinities ranging from 0 to >50 ppt (Brockmann 1974, Kaill 1967). Though the range of F. carpio is mostly subtropical, it has been documented to withstand a wide range of temperatures, from 6 to 37.8 °C (Gilmore et al. 1978, Kaill 1967).
Dissolved Oxygen: Many areas in salt marsh and mangrove habitats may be characterized by low dissolved oxygen (DO) levels due to decaying organic matter and little water movement. However, F. carpio is sensitive to hypoxia, showing stress at DO levels of 6-8 mg/kg-1, and is nearly incapacitated at a range of 4-5 mg/kg-1 (Kaill 1967).
Trophic Mode: The diet of F. carpio appears to vary with salinity (Ley et al. 1994), which is most likely the result of habitat composition in these areas. Where the salinity range is wide, killifish consumed mostly algae. In areas where salinity was less variable, F. carpio preyed on more benthic invertebrates. Populations have been found to ingest copepods, gastropods, amphipods, eggs and detritus (Motta et al. 1995, Odum & Heald 1972).
Predators: Few predators are documented for this species, but individuals are likely preyed upon by larger fishes, wading birds and crabs.
Associated Species: No known obligate associations exist for F. carpio. However, goldspotted killifish are associated with several organisms common to mangroves, mosquito impoundments, seagrass beds and salt marshes.
References: Brockmann, FW. 1974. Seasonality of fishes in a south Florida brackish canal. FL Sci. 37: 65-70. Gilmore, RG, Bullock, LH & FH Berry. 1978. Hypothermal mortality in marine fishes of south-central Florida. January, 1977. NE Gulf Sci. 2: 77-97.
Kaill, WM. 1967. Ecology and behavior of the cyprinodontid fishes Jordanella floridae (Goode & Bean), Floridichthys carpio (Günther) and Cyprinodon variegatus (Lacépède). PhD Dissertation. Cornell University. Ithaca, NY. USA. 172 pp.
Lewis, RR III & RG Gilmore. 2007. Important considerations to achieve successful mangrove forest restoration with optimum fish habitat. Bull. Mar. Sci. 80: 823-837.
Ley, JA, Montague, CL & CC McIvor. 1994. Food habits of mangrove fishes: a comparison along estuarine gradients in northeastern Florida Bay. Bull. Mar. Sci. 54: 881-899.
Loftus, WF & JA Kushlan. 1987. Freshwater fishes of southern Florida. Bull. Fla. State Mus. Biol. Sci. 31: 147-344.
Motta, PJ, Clifton, KB, Hernandez, P, Eggold, BT, Giordano, SD & R Wilcox. 1995. Feeding relationships among nine species of seagrass fishes of Tampa Bay, Florida. Bull. Mar. Sci. 56: 185-200.
Nordlie, FG. 2000. Patterns of reproduction and development of selected resident teleosts of Florida salt marshes. Hydrobiol. 434: 165-182.
Nordlie, FG. 2006. Physicochemical environments and tolerances of cyprinodontid fishes found in estuaries and salt marshes of eastern North America. Rev. Fish Biol. Fisheries. 16: 51-106.
Nordlie, FG & SJ Walsh. 1989. Adaptive radiation in osmotic regulatory patterns among three species of cyprinodontids (Teleostei: Atherinomorpha). Physiol. Zool. 62: 1203-1218.
Odum & Heald. 1972. Trophic analyses of an estuarine mangrove community. Bull. Mar. Sci. 22: 671-738.
Powell, AB, Thayer, G, Lacroix, M & R Cheshire. 2007. Juvenile and small resident fishes of Florida Bay, a critical habitat in the Everglades National Park, Florida. NOAA Professional Paper NMFS 6: 105-108. National Marine Fisheries Service. Seattle, WA. USA.
Robins, CR & GC Ray. 1986. A field guide to Atlantic coast fishes of North America. Houghton Mifflin Co. New York. USA. 354 pp. Schmidt, TW. 1979. 1979 ecological study of fishes and the water quality characteristics of Florida Bay, Everglades National Park, Florida. NPS Special Report 01-02. US National Park Service. Homestead, FL. USA.
Shirley, M, O’Donnell, P, McGee, V & T Jones. 2004. Nekton species composition as a biological indicator of altered freshwater inflow: a comparison of three south Florida estuaries. In: Bortone, SA, ed. Estuarine indicators. 351-361. CRC Press. Boca Raton, FL.
USA Sogard, SM, Powell, GVN & JG Holmquist. 1987. Epibenthic fish communities on Florida Bay banks: relations with physical parameters and seagrass cover. Mar. Ecol. Prog. Ser. 40: 25-39.
Sogard, SM, Powel, GVN & JG Holmquist. 1989. Utilization by fishes of shallow, seagrass-covered banks in Florida Bay: 1. Species composition and spatial heterogeneity. Env. Biol. Fish. 24: 53-65. Stevens, PW. 2002. Test of salt marsh as a site of production and export of fish biomass with implications for impoundment management and restoration. PhD Dissertation. University of Florida. Gainesville, FL. USA. 195 pp.
Thayer, GW, Colby, DR & WF Hettler. 1987. Utilization of the red mangrove prop root habitat by fishes in south Florida Bay. Mar. Ecol. Prog. Ser. 35: 25-38.